Methods and apparatus for well construction

Abstract

A method of constructing a well comprising a borehole drilled through underground formations, comprises: positioning at least one device on the outside of the tubular string (e.g. a drill string or casing string), the device being operable to move between first and second configurations; positioning a tubular string in the borehole with the device positioned in the annular space between the tubular string and the borehole wall in its first configuration so as to interact with the tubular string and the borehole while allowing borehole fluid to flow along the annular space and around the device; and operating the device so as to move it from its first configuration to expand into its second configuration in which it substantially fills at least part of the annular space so as to inhibit flow of fluids along the borehole in the space. Apparatus comprises: a string of tubular members; at least one device positioned on the outside of the string, the device being operable to expand between: (i) a first configuration in which, when the tubular string is positioned in the borehole with the device located in the annular space between the tubular string and the borehole wall, interacts with the tubular string and the borehole while allowing borehole fluid to flow along the annular space and around the device; and (ii) a second configuration in which it substantially fills at least part of the annular space so as to prevent flow of fluids along the borehole in the space.

1. A method of constructing a well comprising a borehole drilled through underground formations, the method comprising:
 positioning at least one device on the outside of the tubular string, the device being operable to move between first and second configurations; 
 positioning a tubular string in the borehole with the device positioned in the annular space between the tubular string and the borehole wall in its first configuration so as to interact with the tubular string and the borehole while allowing borehole fluid to flow along the annular space and around the device; and 
 applying a trigger to initiate expansion of the device between the first and second configurations 
 operating the device so as to move it from its first configuration to expand into its second configuration in which it substantially fills at least part of the annular space so as to inhibit flow of fluids along the borehole in the space 
 wherein expansion is initiated by irradiating the device with microwave or ultrasonic radiation. 
 
   
   
     2. A method as claimed in  claim 1 , comprising positioning multiple devices at locations spaced along the tubular string. 
   
   
     3. A method as claimed in  claim 1 , further comprising pumping cement into the annulus before operating the device to move to its second configuration. 
   
   
     4. A method as claimed in  claim 1 , comprising operating the device to move to its second configuration while the annulus is substantially free of cement. 
   
   
     5. Apparatus for constructing a well comprising a borehole drilled through underground formations; the apparatus comprising:
 a string of tubular members; 
 at least one device positioned on the outside of the string, the device being operable to expand, when irradiated with microwave or ultrasonic radiation between: 
 (i) a first configuration in which, when the tubular string is positioned in the borehole with the device located in the annular space between the tubular string and the borehole wall, interacts with the tubular string and the borehole while allowing borehole fluid to flow along the annular space and around the device; and 
 (ii) a second configuration in which it substantially fills at least part of the annular space so as to inhibit flow of fluids along the borehole in the space 
 wherein the device is at least partially formed from a swellable or expandable polymer or an electroactive cross-linked polymer or both. 
 
   
   
     6. Apparatus as claimed in  claim 5 , wherein the device comprises first members which, when the tubular string is located in the borehole and the device is in its first configuration, extend between the tubular string and the borehole wall so as to maintain the position of the tubular string in the borehole. 
   
   
     7. Apparatus as claimed in  claim 5 , wherein the device comprises second members which, when the tubular string is located in the borehole and the device is in its first configuration, interact with fluid flowing in the annular space so as to modify its flow in the region of the device. 
   
   
     8. Apparatus as claimed in  claim 5 , comprising rings of accelerated swellable material positioned at locations along the tubular string.